Method and apparatus for power scaling for multi-carrier wireless terminals

ABSTRACT

A wireless transmit/receive unit (WTRU) may determine transmission power levels for uplink channels for uplink component carriers. A transmission power level of a physical uplink shared channel (PUSCH) without control data may be scaled before a PUSCH with control data. A PUSCH without control data may be scaled before a physical uplink control channel (PUCCH) with control data. A secondary component carrier may be scaled before a primary component carrier.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/230,929, filed Mar. 31, 2014, which is a continuation of U.S. patentapplication Ser. No. 12/766,400, filed Apr. 23, 2010, which issued asU.S. Pat. No. 8,700,084 on Apr. 15, 2014, which claims the benefit ofU.S. provisional application No. 61/172,109 filed Apr. 23, 2009; U.S.provisional application No. 61/218,830 filed Jun. 19, 2009; and U.S.provisional application No. 61/235,803 filed Aug. 21, 2009, the contentsof which are hereby incorporated by reference herein.

BACKGROUND

Radio transmitters are generally limited in total transmit power, alimit imposed by regulatory agencies or by the battery or poweramplifier technology. This power limitation may result in reduced radiocoverage. For example, as a wireless transmit/receive unit (WTRU) movesaway from its base station, it typically increases its transmissionpower to maintain the same level of quality at the base station. TheWTRU output power is controlled by the base station via a power controlloop. When the WTRU reaches its maximum power and may no longer increaseits power to maintain the signal quality desired at the base station,power scaling is applied. This may occur for example when the WTRU isclose to cell-edge, or when the WTRU enters a region of deep signalfade.

Wireless communication systems keep evolving to meet the needs forproviding continuous and faster access to a data network. In order tomeet these needs, wireless communication systems may use multiplecarriers for the transmission of data. A wireless communication systemthat uses multiple carriers for the transmission of data may be referredto as a multi-carrier system. The use of multiple carriers is expandingin both cellular and non-cellular wireless systems.

A multi-carrier system may increase the bandwidth available in awireless communication system according to a multiple of how manycarriers are made available. For instance, a dual carrier system maydouble the bandwidth as compared to a single carrier system and atri-carrier system may triple the bandwidth as compared to a singlecarrier system and so on. In multi-carrier systems, the WTRU maytransmit, for example, over two adjacent carriers. A power amplifier maybe assumed to be common to the multiple carriers such that the totalpower is a shared resource between the multiple carriers. Methods andapparatus for power scaling for multi-carrier wireless terminals aredesired.

SUMMARY

Methods and apparatus for power scaling for multi-carrier wirelessterminals are disclosed. Methods and mechanisms are provided for powerscaling when a multi-carrier WTRU reaches its maximum output power.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1 shows an example wireless communication system including aplurality of wireless transmit/receive units (WTRUs), a Node-B, acontrolling radio network controller (CRNC), a serving radio networkcontroller (SRNC), and a core network;

FIG. 2 shows example functional block diagrams of the WTRU and theNode-B of the wireless communication system of FIG. 1;

FIG. 3 shows an example wireless communication system/access network oflong term evolution (LTE);

FIG. 4 shows example block diagrams of a WTRU and a base station of theLTE wireless communication system of FIG. 3;

FIG. 5 shows an example of wireless communications using multiplecarriers;

FIG. 6A shows an example flowchart for power scaling for multi-carrierWTRUs;

FIG. 6B shows another example flowchart for power scaling formulti-carrier WTRUs; and

FIG. 7 shows another example flowchart for power scaling formulti-carrier WTRUs.

DETAILED DESCRIPTION

When referred to hereafter, the terminology “wireless transmit/receiveunit (WTRU)” includes but is not limited to a user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a computer, or any othertype of device capable of operating in a wireless environment. Whenreferred to hereafter, the terminology “base station” includes but isnot limited to a Node-B, a site controller, an access point (AP), or anyother type of interfacing device capable of operating in a wirelessenvironment.

Multiple uplink and downlink carriers may be configured for the WTRU.The multiple carriers may or may not be adjacent and may or may not beon the same frequency or radio band and/or range of frequencies. In oneembodiment, the multiple carriers may include, but are not limited to,four downlink carriers adjacent in the same band with one or two uplinkcarriers in the same band. In another embodiment, the multiple carriersmay include, but are not limited to, two pairs of two adjacent downlinkcarriers over two different bands and two uplink carriers in therespective bands. In yet another embodiment, the multiple carriers mayinclude, but are not limited to, three adjacent downlink carriers in thesame band with one or two (adjacent) uplink carriers also in the sameband. Multiple uplink and downlink carriers may also be configured tooperate in symmetric and asymmetric configurations with respect tocarrier size and the number of carriers. Carriers may also be referredto as component carriers.

In general, the network may assign at least one downlink and/or at leastone uplink carrier as an anchor downlink carrier and an anchor uplinkcarrier, respectively. In multi-carrier operation, a WTRU may beconfigured to operate with two or more carriers. Carriers may also bereferred to as, or by, frequencies. Each of these carriers may havedistinct characteristics and logical associations with the network andthe WTRU, and the operating frequencies may be grouped and referred toas an anchor or primary carrier and a supplementary or secondarycarrier. If more than two carriers are configured, the WTRU may have orbe configured to receive more than one primary carrier and/or more thanone secondary carrier(s). For example, the anchor carrier may be definedas the carrier for carrying a specific set of control information fordownlink/uplink transmissions. Any carrier that is not assigned as ananchor carrier may be a supplementary carrier. Alternatively, thenetwork may not assign an anchor carrier and no priority, preference, ordefault status may be given to any downlink or uplink carriers.Hereinafter, the terms “anchor carrier”, “primary carrier”, “uplinkcarrier 1”, “first carrier”, and “first uplink carrier”, are usedinterchangeably herein for convenience. Similarly, the terms“supplementary carrier”, “secondary carrier”, “uplink carrier 2”,“second carrier”, and “second uplink carrier” are also usedinterchangeably herein. Although the term “uplink” is used, the term“downlink” is equally applicable. For multi-carrier operation, more thanone supplementary carrier or secondary carrier may exist.

The terminology “anchor carrier” may refer to the downlink frequencycarrier associated with an uplink frequency carrier assigned to theWTRU, and the terminology “supplementary carrier” may refer to thedownlink frequency carrier which is not the anchor carrier. The uplink“anchor” carrier may refer to the uplink carrier associated with thedownlink anchor carrier either via explicit configuration or by implicitassociation via the specific uplink/downlink carrier spacing.

The term downlink “anchor” carrier may refer to the downlink carriercarrying downlink control channels such as, but not limited to, afractional dedicated physical channel (F-DPCH) (shown in FIG. 5), anenhanced-absolute grant channel (E-AGCH), physical downlink controlchannel (PDCCH) and other such channels. Other physical channels such asthe common pilot channel (CPICH), high-speed shared control channel(HS-SCCH) and high-speed physical downlink shared channel (HS-PDSCH) maybe read from any downlink carrier, such as the supplementary orsecondary carriers. When more than one downlink carrier carries downlinkcontrol channels associated with one or more uplink carriers, thedownlink “anchor” carrier may refer to a downlink carrier configuredwith an “anchor” carrier attribute. Alternatively, the term downlink“anchor” carrier may refer to the downlink carrier on which a servinghigh-speed downlink shared channel (HS-DSCH) cell is transmitted.Optionally, if a single downlink carrier is configured for the WTRU,then it may be the primary downlink carrier.

The term uplink “anchor” carrier may refer to the uplink carrier overwhich the HS-DPCCH is transmitted. Alternatively, it may refer to thecarrier over which the DPDCH is transmitted, if configured. In anotherembodiment, it may refer to the carrier over which the Signaling RadioBearers (SRBs) or other dedicated control messages are carried. In yetanother embodiment, the anchor carrier may be the uplink carrierassociated with the downlink anchor carrier, e.g., the serving HS-DSCHcell. Although SRBs may be used as an example of a dedicated controlmessage in the description, SRBs may also equivalently refer to otherdedicated control messages or any higher priority messages that may becarried on the physical data channel.

Embodiments described herein provide several approaches for implementingpower scaling for uplink transmissions across multiple uplink carriers.Embodiments described herein are applicable to any number of uplinkcarriers. In general, the embodiments described herein are applicable toWTRUs where power may be shared across all carriers or a subset ofcarriers or a maximum total power constraint across all carriers or asubset of carriers are imposed. For example, but not limited to, it maybe applicable to WTRUs having a single power amplifier that is sharedamong multiple carriers.

FIG. 1 shows an example wireless communications system 100 where uplinktransmissions are handled using multiple carriers 160 and downlinktransmissions are handled using multiple carriers 170. The wirelesscommunication system 100 includes a plurality of WTRUs 110, a Node-B120, a CRNC 130, a SRNC 140, and a core network 150. The Node-B 120 andthe CRNC 130 may collectively be referred to as the UTRAN 180.

As shown in FIG. 1, the WTRUs 110 are in communication with the Node-B120, which is in communication with the CRNC 130 and the SRNC 140.Although three WTRUs 110, one Node-B 120, one CRNC 130, and one SRNC 140are shown in FIG. 1, it should be noted that any combination of wirelessand wired devices may be included in the wireless communication system100.

FIG. 2 is a functional block diagram of the WTRU 110 and the Node-B 120of the wireless communication system 100 of FIG. 1. As shown in FIG. 2,the WTRU 110 is in communication with the Node-B 120 using multipleuplink carriers 260 and multiple downlink carriers 270. WTRU 110 andNode-B 120 are configured to perform a method of power scaling onmultiple uplink carriers.

The WTRU 110 includes a processor 215, a receiver 216, a transmitter217, a memory 218, an antenna 219, and other components (not shown) thatmay be found in a typical WTRU. The antenna 219 may include a pluralityof antenna elements or a plurality of antennas may be included in theWTRU 110. The memory 218 is provided to store software includingoperating system, application, and other modules or components. Theprocessor 215 is provided to perform, alone or in association withsoftware and/or any one or more of the components, a method whereinuplink transmissions from the WTRU 110 are transmitted to the Node-B 120using multiple uplink carriers in accordance with the power scalingexamples described herein. The receiver 216 and the transmitter 217 arein communication with the processor 215. The receiver 216 and thetransmitter 217 are capable of receiving and transmitting one or morecarriers simultaneously. Alternatively, multiple receivers and/ormultiple transmitters may be included in the WTRU 110. The antenna 219is in communication with both the receiver 216 and the transmitter 217to facilitate the transmission and reception of wireless data.

The Node B 120 includes a processor 225, a receiver 226, a transmitter227, a memory 228, an antenna 229, and other components (not shown) thatmay be found in a typical base station. The antenna 229 may include aplurality of antenna elements or a plurality of antennas may be includedin the Node B 220. The memory 228 is provided to store softwareincluding operating system, application, and other modules orcomponents. The processor 225 is provided to perform, alone or inassociation with software and/or any one or more of the components, amethod wherein uplink transmissions from the WTRU 110 are transmitted tothe Node-B 120 using multiple uplink carriers in accordance with thepower scaling examples described herein. The receiver 226 and thetransmitter 227 are in communication with the processor 225. Thereceiver 226 and the transmitter 227 are capable of receiving andtransmitting one or more carriers simultaneously. Alternatively,multiple receivers and/or multiple transmitters may be included in theNode B 220. The antenna 229 is in communication with both the receiver226 and the transmitter 227 to facilitate the transmission and receptionof wireless data.

FIG. 3 shows another example wireless communications system 300 whereuplink transmissions are handled using multiple uplink carriers 350 anddownlink transmissions are handled using multiple downlink carriers 360.In particular, FIG. 3 shows a Long Term Evolution (LTE) wirelesscommunication system/access network 300 that includes anEvolved-Universal Terrestrial Radio Access Network (E-UTRAN) 305. TheE-UTRAN 305 includes a WTRU 310 and several evolved Node-Bs, (eNBs) 320.The WTRU 310 is in communication with an eNB 320. The WTRU 310 and eNB320 may communicate using uplink component carriers 350 and downlinkcomponent carriers 360. The eNBs 320 interface with each other using anX2 interface. Each of the eNBs 320 interface with a Mobility ManagementEntity (MME)/Serving GateWay (S-GW) 330 through an S1 interface.Although a single WTRU 310 and three eNBs 320 are shown in FIG. 3, itshould be apparent that any combination of wireless and wired devicesmay be included in the wireless communication system access network 300.

FIG. 4 is an example block diagram of an LTE wireless communicationsystem 300 including the WTRU 310, the eNB 320, and the MME/S-GW 330. Asshown in FIG. 4, the WTRU 310 is in communication with the eNB 320 andboth are configured such that uplink transmissions from the WTRU 310 aretransmitted to the eNB 320 using multiple carriers 450, and downlinktransmissions from the eNB 320 are transmitted to the WTRU 310 usingmultiple downlink carriers 460. The WTRU 310, the eNB 320 and theMME/S-GW 330 are configured to perform a method of power scaling onmultiple uplink carriers.

In addition to the components that may be found in a typical WTRU, theWTRU 310 includes a processor 416 with an optional linked memory 422, atleast one transceiver 414, an optional battery 420, and an antenna 418.The processor 416 is configured for power scaling on multiple uplinkcarriers. The transceiver 414 is in communication with the processor 416and the antenna 418 to facilitate the transmission and reception ofwireless communications. In case a battery 420 is used in the WTRU 310,it powers the transceiver 414 and the processor 416.

In addition to the components that may be found in a typical eNB, theeNB 320 includes a processor 417 with an optional linked memory 415,transceivers 419, and antennas 421. The processor 417 is configured toperform power scaling on multiple uplink carriers. The transceivers 419are in communication with the processor 417 and antennas 421 tofacilitate the transmission and reception of wireless communications.The eNB 320 is connected to the Mobility Management Entity/ServingGateWay (MME/S-GW) 330 which includes a processor 433 with an optionallinked memory 434.

A Wideband Code Division Multiple Access (WCDMA) Frequency DivisionDuplex (FDD) WTRU transmits both data and control channelssimultaneously using code division multiple access. In WCDMA FDD, thepower of every channel is dependent on a power offset relative to thepower of the Dedicated Physical Control Channel (DPCCH). The power ofthe DPCCH is controlled by base stations on the active set such that acertain level of quality is reached. Typically, the power ratio for thecontrol channels are configured by the network, whereas the power ratiosfor the data channels are also determined based on the transmitted datarate.

Power scaling for WTRUs may depend, for example, on whether EnhancedDedicated Channel (E-DCH) is configured. For the case where the E-DCH isnot configured, and the total WTRU transmit power after applying theDPCCH power adjustments and gain factor may exceed the maximum allowedvalue, the WTRU may apply additional scaling to the total transmit powerso that it is equal to the maximum allowed power. This additionalscaling may be such that the power ratio between DPCCH and DedicatedPhysical Data Channel (DPDCH) and DPCCH and High Speed DedicatedPhysical Control Channel (HS-DPCCH) is maintained as required. Thus whenthe E-DCH is not configured, the power scaling mechanism maintains thepower ratio between the different channels.

For the case where the E-DCH is configured, the rule is different. TheWTRU may first reduce all the E-DCH Dedicated Physical Data Channel(E-DPDCH) gain factors, β_(ed,k), by an equal scaling factor torespective values, β_(ed,k,reduced), so that the total transmit powermay be equal to the maximum allowed power. In case no DPDCH isconfigured and regardless of the applied uplink modulation, if anyβ_(ed,k,reduced)/β_(c) is less than β_(ed,k,reduced,min)/β_(c), thenβ_(ed,k) shall be set to β_(ed,k,min) such that β_(ed,k,min)/β_(c)=min(β_(ed,k,reduced,min)/β_(c), β_(ed,k,original)/β_(c)), whereβ_(ed,k,original) denotes the E-DPDCH gain factor before reduction andβ_(ed,k,reduced,min) is configurable by higher layers.

The WTRU may then apply additional power scaling to the total transmitpower so that it is equal to the maximum allowed power in certain cases.Power scaling may be applied if the DPDCH is configured and the totalWTRU transmit power would still exceed the maximum allowed value eventhough discontinuous transmission (DTX) is used on all the E-DPDCHs. Itmay also be applied if no DPDCH is configured and the total WTRUtransmit power would still exceed the maximum allowed value even thoughβ_(ed,k) is equal to β_(ed,k,min) for all k.

Any additional power scaling of the total transmit power shall be suchthat the power ratio between the DPCCH and the DPDCH, between the DPCCHand the HS-DPCCH, and between the DPCCH and the E-DPCCH, is maintainedas required and such that the power ratio between each E-DPDCH and DPCCHremains as required by β_(ed,k,min)/β_(c) if DTX is not used on theE-DPDCH.

The rules for power scaling ensure that power is devoted to the controlchannels and the data channels carrying dedicated control messages suchas the Signaling Radio Bearers (SRBs). When the DPDCH and the E-DCH areconfigured, the WTRU may reduce the power of the E-DCH completely beforeapplying power scaling equally to all other channels. In short, thisapproach allows the SRBs mapped to the DPDCH to be transmitted at theproper power at the expense of the E-DCH. When there is no DPDCH, theSRBs are necessarily mapped to the E-DCH and for this reason a minimumpower ratio β_(ed,k,reduced,min) is provided to the E-DCH. DTX will notbe applied to the E-DCH in this case.

Referring now to FIG. 5, there is shown a Node B 505 and WTRU 510communicating using multiple uplink carriers 520 and 540 and multipledownlink carriers 570 and 590. The multiple downlink carriers 570 and590 may carry certain power information from the Node B 510 to the WTRU505. The power scaling examples described herein may be used inconjunction with the dedicated physical control channel (DPCCHs) 525 and545 carried by uplink carriers 520 and 540, respectively. Moreover, thepower scaling examples may be applied to the Enhanced Dedicated Channels(E-DCH) Dedicated Physical Data Control Channel (E-DPDCH) carried by theuplink carriers 520 and 540, respectively. It is noted that whilespecific channels are shown being carried by uplink and downlinkcarriers in the figures shown herein, any applicable channel may becarried in such carriers. Alternatively, the power scaling examplesdescribed herein may be used in conjunction with a physical uplinkcontrol channel (PUCCH) and may be applied to a physical uplink sharedchannel (PUSCH). The PUSCH(s) may be carried on uplink carriers 520 and540.

It is also noted that although the embodiments described herein aredescribed with reference to channels associated with Third GenerationPartnership Program (3GPP) Releases 4 through 9, it should be noted thatthe embodiments are applicable to further 3GPP releases (and thechannels used therein) such as LTE Release 10 as well as any other typeof wireless communication system, and the channels used therein. Itshould also be noted that the embodiments described herein may beapplicable in any order or in any combination. While embodiments may bedescribed in the context of 3GPP Wideband Code Division Multiple Access(WCDMA) Frequency Division Duplex (FDD), the description herein may beapplicable to other wireless technologies. Likewise, where theembodiments are described in the context of dual-carrier uplinkoperations, the description may be extended to support multi-carrieruplink operations which use, for example, simultaneous transmission ofdata and control channels.

When referred to hereafter, the terminology “maximum power limit” mayrefer to one or a combination of the following illustrative meanings.Maximum power limit may refer to the maximum power over all or a subsetof carriers as defined by the WTRU category. It may alternatively referto the maximum power over all or a subset of carriers as configured bythe network. This may be smaller than or equal to the maximum power overall or a subset of carriers as defined by the WTRU category. It may alsorefer to the sum of the maximum power configured by the network for eachof the carriers or group of carriers. The maximum powers for each of thecarriers may or may not be the same.

The power scaling methods and approaches for dual-carrier andmulti-carrier operations described herein may be used in any order andcombination. While the example methods may be described in terms ofpower, the examples may equivalently be described in terms of amplitudeor gain factors. While the example methods may be described with respectto DPCCH, E-DPDCH, PUCCH, PUSCH and other illustrative channels, theexamples are also applicable to control and data channels in general.Unless specified otherwise, the proposed methods for power scaling applywhen the WTRU is configured for dual-carrier or multi-carrier operationsand more than one carrier is being transmitted by the WTRU.

In general, as shown in FIG. 6A, the WTRU may execute the followingprocedure. If the total WTRU transmit power (the WTRU transmit power maycorrespond to the power after applying DPCCH power adjustments and gainfactor as an example) does not exceed the maximum allowed value (605)then transmission is allowed (610). If the total WTRU transmit powerexceeds the maximum allowed value, then the WTRU performs power scalingon a group channels in accordance with a rule or criteria until thetotal WTRU transmit power no longer exceeds the maximum allowed value orminimum transit power levels are reached (615). For example, the groupof channels may be data channels as shown in FIG. 6A. The group ofchannels may include channels carrying user information (e.g., E-DCH)and optionally include associated control channels (e.g., E-DPCCH). Ifthe total WTRU transmit power does not exceed the maximum power value(620), then transmission is allowed (610). If the total WTRU transmitpower exceeds the maximum allowed value, then the WTRU may need toperform power scaling on another group of channels under certainconditions as described herein (625). For example, this other group ofchannels may be control channels as shown in FIG. 6A. If the total WTRUpower does not exceed the maximum allowed value (630), then transmissionis allowed (610). If the total WTRU transmit power still exceeds themaximum allowed value (630), then the WTRU may need to performadditional power scaling (635). FIG. 6A is illustrative and the WTRU mayperform power scaling in any order and in any combination.

Alternatively, as shown in FIG. 6B, the WTRU may execute the followingprocedure. If the total WTRU transmit power (the WTRU transmit power maybe correspond to the power after applying DPCCH power adjustments andgain factor, as an example), does not exceed the maximum allowed value(650) then transmission is allowed (655). If the total WTRU transmitpower exceeds the maximum allowed value, then the WTRU performs powerscaling on a group of channels (denoted as data channels in FIG. 6B) inaccordance with a rule or criteria until the total WTRU transmit powerno longer exceeds the maximum allowed value or minimum transit powerlevels are reached (660). The group of channels may include channelscarrying user information (e.g., E-DCH) and optionally includeassociated control channels (e.g., E-DPCCH). If the total WTRU transmitpower does not exceed the maximum power value (665), then transmissionis allowed (655). If the total WTRU transmit power still exceeds themaximum allowed value (665), then the WTRU may need to performadditional power scaling (670). FIG. 6B is illustrative and the WTRU mayperform power scaling in any order and in any combination.

The WTRU may perform one or more of the following methods, in any orderor combination, and may repeat one or more of the following methods.

In one example method for performing power scaling on a data channel(e.g., 615 in FIG. 6), the WTRU may scale down the power of the E-DPDCHuntil the total WTRU transmit power no longer exceeds the maximumallowed value. In another example method, a minimum power scaling may beprovided for the E-DPDCH of one or more carriers. In yet another examplemethod, a minimum power scaling may be provided for the E-DPDCH of theanchor carrier (which may carry the signaling radio bearers (SRBs)) andno minimum power scaling may be applied to any of the supplementarycarriers. For the minimum power scaling methods, the WTRU may receivethe minimum power scaling configuration from the network via radioresource controller (RRC) signaling or higher layer signaling. In stillanother example, if different maximum power levels are set for eachcarrier, the WTRU may scale power on each of the carriers as describedherein to the maximum power level for each of the carriers.

Power scaling on the data channel may be implemented using one or acombination of the example approaches described herein. In one exampleapproach, the UL carriers may all be scaled equally. As an example ofthis first approach, the E-DPDCH power of all UL carriers are scaledequally until the total WTRU transmit power no longer exceeds themaximum allowed value or the minimum power has been reached on all thecarriers. In another example of this approach, the PUSCH power of allcarriers are scaled equally until the total WTRU transmit power nolonger exceeds the maximum allowed value or the minimum power has beenreached on all carriers.

In another example approach, the WTRU may first scale all ULsupplementary carriers equally, and then scale the anchor carrier. As anexample of this approach, the E-DPDCH power of all UL supplementarycarriers are scaled equally until the total WTRU transmit power nolonger exceeds the maximum allowed value or the minimum power has beenreached on all the supplementary carriers. If the total WTRU transmitpower still exceeds the maximum allowed value, then power scaling may beapplied to anchor carrier's E-DPDCH. In another example of thisapproach, the PUSCH power of all UL supplementary carriers are scaledequally until the total WTRU transmit power no longer exceeds themaximum allowed value or the minimum power has been reached on all thesupplementary carriers.

In another example approach, the WTRU may scale the power with adifferent weight on each carrier. In an example of this approach, thepower of the E-DPDCH is scaled differently for each carrier. By applyinga different weighting to each carrier, some carriers may be scaled moreaggressively than others. The actual power scaling for each carrier thentakes the form of a per-carrier weight combined with a common powerscaling factor which may applied to more than one carrier. Theper-carrier weights may be determined, for example, by using one or moreof the techniques described herein, individually or in any combination.

In another example approach, the per-carrier weights are grant based. Inthis approach, the E-DPDCH per-carrier weights depend on the servinggrant of each carrier. In another example technique, the per-carrierweights are predefined. In this technique, the E-DPDCH per-carrierweights depend on a configured or pre-configured set of weights. Thepredefined weights may be preset, configured by the network or signaledvia the RRC or higher layers. In another example approach, theper-carrier weights depend on carrier identity or type (e.g., anchorversus supplementary). In this approach, the E-DPDCH per-carrier weightsdepend on the carrier type (anchor or supplementary). A configured orpre-defined set of per-carrier weights for power scaling of anchor andsupplementary carrier or carriers may be used. These may be preset,configured by the network or signaled via the RRC or higher layers. Inanother example approach, the per-carrier weights may depend on themaximum power defined by the network for each carrier. The weights mayalso depend on any weighting methods in addition to the scaling rulesbased on the network defined per carrier maximum power.

In another example approach, the WTRU may scale one carrier at a time.As part of this approach, the power scaling may be applied to a datachannel on a selected carrier until the WTRU transmit power no longerexceeds the maximum allowed value, or until the data channel minimumpower is reached, or the power of the data channel is zero, in whichcase the data channel may optionally be in DTX mode. If the minimumpower of the data channel is reached in the given carrier and additionalscaling is required, the WTRU selects another carrier on which powerscaling may be performed. When the WTRU transmit power no longer exceedsthe maximum allowed value, the WTRU no longer needs to perform powerscaling on the other carriers and the procedure is complete. In thisapproach, each carrier is processed successively (separately) for powerscaling, and the order of processing may be determined using one or moreof the techniques described herein, in any order or combination. As anexample of this approach, the WTRU would start by reducing all theE-DPDCH gain factors on a selected carrier until the WTRU no longerexceeds the maximum power or is down to a minimum gain factor on thiscarrier. If further scaling is required (i.e., minimum gain factor hasbeen reached on the selected carrier and additional scaling isrequired), the WTRU selects another carrier for reduction of its E-DPDCHgain factor (at most down to a minimum gain factor). The minimum gainfactor may be pre-configured or signaled to the WTRU through higherlayer signaling. The minimum gain factor may be defined per-carrier or asingle value may be used for all carriers.

In another example approach, processing order may depend on anchorversus supplementary. In this technique, the power scaling may be firstapplied to the E-DPDCH transmitted on the supplementary carrier (withoutaffecting the E-DPDCH on the anchor carrier). In case more than onesupplementary carrier is configured, then the same power scaling may beapplied to all supplementary carriers. Alternatively, a different powerscaling may be applied. This may depend for instance on the grant or apre-defined scaling weight as discussed herein. The power of the E-DPDCHon the anchor may not be scaled until the power from all supplementarycarriers' E-DPDCH have been scaled down to zero, and the total WTRUtransmit power still exceeds the maximum allowed power. In onealternative, the power of the E-DPDCH on the anchor may not be scaleduntil the power from all supplementary carriers' E-DPDCH have beenscaled down to zero, and the power of the associated E-DPCCH have alsobeen scaled down to zero, and the total WTRU transmit power stillexceeds the maximum allowed power. In another alternative, the E-DPDCHon the anchor may not be scaled until all supplementary carriers arede-activated.

In another example approach, processing order may be predefined. In thistechnique, the power scaling may be first applied to the E-DPDCHtransmitted on the anchor carrier. The power of the E-DPDCH on thesupplementary carrier (or carriers) may not be scaled until the powerfrom the anchor carrier's E-DPDCH has been scaled down to zero or to theminimum value configured, and the total WTRU transmit power stillexceeds the maximum allowed power. Alternatively, the power of theE-DPDCH on the supplementary carrier (or carriers) may not be scaleduntil the power from the anchor carrier's E-DPDCH has been scaled downto zero or to the minimum value configured, the power of the associatedE-DPCCH has also been scaled down to zero, and the total WTRU transmitpower still exceeds the maximum allowed power.

In another example approach, the processing order may be pre-defined. Inthis approach, the order of processing carriers for power scaling ispre-defined or configured by the network. The WTRU processes eachcarrier successively. For each carrier, power scaling is applied to theE-DPDCH until the WTRU transmit power no longer exceeds the maximumallowed value, or until the E-DPDCH minimum power is reached, or thepower of the E-DPDCH is zero in which case the E-DPCCH may optionallynot be transmitted (or equivalently be in discontinuous transmission(DTX) mode). When the WTRU transmit power no longer exceeds the maximumallowed value, the WTRU no longer needs to perform power scaling on theother carriers and the procedure is complete.

In another example approach, the processing order may depend on a WTRUgrant. In this technique, the order of power scaling carrier depends onthe serving grant for each carrier. For example the power scaling may beapplied to the carriers in increasing (or decreasing) order of servinggrant. The WTRU processes each carrier successively. For each carrier,power scaling is applied to the E-DPDCH until the WTRU transmit power nolonger exceeds the maximum allowed value, or until the E-DPDCH minimumpower is reached, or the power of the E-DPDCH is zero in which case theE-DPCCH may optionally be in DTX mode. When the WTRU transmit power nolonger exceeds the maximum allowed value, the WTRU no longer needs toperform power scaling on the other carriers and the procedure iscomplete.

In another example approach, the processing order may depend on a powermetric (e.g., power headroom or power of UL reference or controlchannel) of each carrier. In this approach, the order of power scalingcarrier depends on the power metric of each carrier. For example, thepower scaling may be applied to the carriers in increasing (ordecreasing) order of the power metric. The power metric may be the WTRUpower headroom (UPH), for example calculated based on the maximumallowed power and DPCCH transmit power averaged over a short period(e.g.: 3 radio slots) or alternatively the power metric may be theconventional WTRU power headroom (UPH). Alternatively, the power metricmay be defined as the DPCCH power over each carrier. As an example ofthis approach, the WTRU first selects and processes the carrier havingthe highest DPCCH power. Power scaling is then applied to the E-DPDCHuntil the WTRU transmit power no longer exceeds the maximum allowedvalue, or until the E-DPDCH minimum power is reached, or the power ofthe E-DPDCH is zero in which case the E-DPCCH may optionally be in DTXmode. When the WTRU transmit power no longer exceeds the maximum allowedvalue, the WTRU no longer needs to perform power scaling on the othercarriers and the procedure is complete. If the WTRU transmit power stillexceeds the maximum allowed value, the WTRU then selects the carrierhaving the next highest DPCCH power and repeats the procedure describedabove until the WTRU transmit power no longer exceeds the maximumallowed value or all carriers have been processed.

In another example approach, processing order depends on signaling radiobearers (SRBs). In this technique, the power scaling is first applied tothe E-DPDCH transmitted on the carriers not configured to carry theSRBs. In case more than one such carrier is configured, then the samepower scaling may be applied to all such carriers. Alternatively, adifferent power scaling may be applied to each carrier depending on, forexample, the grant or a pre-defined scaling weight. The power of theE-DPDCH on the carrier carrying the SRB is not scaled until the powerfrom all other carriers' E-DPDCH have been scaled down to zero, andoptionally the power of the associated E-DPCCH have also been scaleddown to zero, and the total WTRU transmit power still exceeds themaximum allowed power. Optionally, the E-DPDCH on the carrier carryingthe SRB is not scaled until all supplementary carriers are de-activated.

In another example approach, processing order may depend on firsttransmission/retransmission. In this approach, the order of powerscaling carrier may depend on whether the transmission is a firsttransmission or a hybrid automatic repeat request (HARQ) retransmissionon each carrier. For example, the WTRU may apply power scaling first tothe carrier for which the transmission is a first HARQ transmission.Alternatively, the WTRU may apply power scaling first to the carrier forwhich the transmission is a HARQ retransmission. The WTRU procedure issimilar to the procedure described herein, but with the carrier orderdependent whether or not the transmission is a first HARQ transmissionor a HARQ retransmission. In case the status of both carriers is thesame (e.g., both are first HARQ transmissions or HARQ retransmissions)then the order may depend on any of the other methods described herein.Described herein is power scaling on control channels as shown as (625),for example, in FIG. 6A. When both the E-DPDCH and E-DPCCH (i.e., theE-DCH) are discontinuously transmitted on a carrier not carrying theDPDCH or the HS-DPCCH, then further processing may be applied. Thisprocessing may be applied when the E-DPDCH has been scaled and the totalWTRU power still exceeds the maximum allowed power, or optionally if theE-DPDCH power for a given carrier is scaled down to zero. In thisinstance, the WTRU may be configured to scale down DPCCH for thatcarrier until maximum power is reached or discontinuous mode may beapplied to the DPCCH, effectively de-activating the carrier.

Described herein is additional scaling as shown as (635), for example,in FIG. 6A. When all supplementary carriers are de-activated and thetotal WTRU transmit power still exceeds the maximum allowed value, theWTRU may be configured to apply additional scaling to the remainingcarrier (the one carrying the DPDCH) as in single-carrier operations.

If the total WTRU transmit power after power scaling according to any ofthe above methods is still above the maximum allowed value, the WTRU mayapply the conventional additional scaling. More specifically, theadditional scaling is applied such that for each carrier the power ratiobetween the DPCCH and the control channel remains and the power ratiobetween the reduced power E-DPDCH and the DPCCH also remains. The powerratio between DPCCH of each carrier remains constant.

Described herein are examples that include a subset of the proceduresand rules described herein. In an example implementation, the additionalpower scaling on the DPCCH for the supplementary carriers is performedbefore scaling the E-DPDCH of the anchor carrier.

In another example implementation, the power scaling is first applied tothe E-DPDCH transmitted on the supplementary carrier (without affectingthe E-DPDCH on the anchor carrier). When the E-DPDCH has been scaled andthe total WTRU power still exceeds the maximum allowed power, then theWTRU scales down DPCCH for that carrier until maximum power is reached.When all supplementary carriers are de-activated and the total WTRUtransmit power still exceeds the maximum allowed value, the WTRU thenapplies additional scaling to the remaining carrier (the one carryingthe DPDCH) as in single-carrier operations.

In another example implementation, power scaling is applied to onecarrier at a time, as needed. Power scaling is initially applied to thedata channel having the worst channel conditions, throughout or othersimilar power based or implied metric. The worst power metric may bedetermined by examining a control channel of the carriers. In general,the higher the power metric for a given control channel, the worse thechannel conditions and the need for greater power to reach a targetsignal-to-noise (SNR) level, quality of service (QoS) or other servicemetric.

An illustrative flowchart 700 of this example implementation is shown inFIG. 7. A WTRU may receive control channel information from a basestation (705). The control channel may be, for example, a DPCCH or anF-DPCH. Transmit power control (TPC) commands extracted from the controlchannel information are applied to set the power levels (710). The WTRUthen determines if the total transmit power after applying the DPCCHpower adjustments and gain factors is greater than the maximum allowedtransmit power for the WTRU (715). If the total transmit power meets oris below the maximum allowed transmit power, then the process iscomplete and transmission may be allowed (720). If the total transmitpower exceeds the maximum allowed transmit power, then the carrier withthe highest DPCCH power or other similar power metric is determined(725). The WTRU then applies power scaling to the data channel, forexample, but not limited to, the E-DPDCH, corresponding to the carrierwith the highest DPCCH power (730). Power scaling of the data channelmay include scaling of only the data channel, e.g., the E-DPDCH, oradditionally scaling of certain control channels that are associatedwith or specific to the data channel, e.g., E-DPDCH. As there may bemultiple E-DPDCHs in the selected carrier, each E-DPDCH in the selectedcarrier may be reduced equally. Power scaling may be applied until thetotal transmit power meets or falls below the maximum allowed transmitpower or reaches a minimum transmit power. The minimum transmit powerfor the E-DPDCH(s) may be predefined or configured by the network viahigher layer signaling.

It is then determined if the total transmit power meets or falls belowthe maximum allowed transmit power (732), and, if so, then power scalingis complete and transmission may be allowed (720). If the total transmitpower still exceeds the maximum allowed transmit power (732), then theWTRU determines if the minimum transmit power has been reached (735). Ifthe minimum transmit power level has not been reached, then powerscaling may still be applied (730). If the minimum transmit power hasbeen reached, then determine if power scaling has been applied to allcarriers (740). If it is determined that power scaling has not beenapplied to all carriers, then the WTRU determines the carrier with thenext highest DPCCH or similar power metric (725) and repeats powerscaling until transmission is allowed or power scaling has been appliedto all active carriers. If the minimum transmit power of the datachannels has been reached for all carriers (740), then additionalscaling may be applied to all carriers (745). Additional scaling of thetotal transmit power reduces the power of all channels on a relativebasis to maintain the power ratios between the data and controlchannels. Additional scaling may be applied until the total transmitpower meets or falls below the maximum allowed transmit power.

Described herein is the impact on enhanced transport format combination(E-TFC). When configured for dual-carrier or multi-carrier operations, aWTRU has the potential to transmit two or more E-DCH transport blocks.In the standard E-TFC selection procedure, the WTRU determines a set ofsupported E-TFCs. These E-TFCs are allowed to be selected to carry datain the upcoming transmission time interval (TTI). To guarantee a minimumtransmission rate, the WTRU may be configured with an E-DCH minimum setE-DCH transport format combination indicator (E-TFCI). All E-TFCIssmaller than or equal to this E-DCH minimum set E-TFCI, or equivalentlyall E-TFCs with corresponding E-TFCI smaller than or equal to this E-DCHminimum set E-TFCI are always considered supported by the E-TFCselection.

When two carriers are configured, a number of possible methods for E-TFCselection may be designed. In one possible set of E-TFC selectionimplementations, the WTRU may have a non-zero E-DCH minimum set E-TFCIconfigured per carrier. In this case, it may be possible for a WTRU(even under power-limited conditions), to generate two or more transportblocks (all of them with an E-TFCI equal to or below the E-DCH minimumset E-TFCI). This particular situation may be undesirable. Inpower-limited conditions it is likely that insufficient power may beallocated for the E-DCH to be received reliably.

To avoid the above situation when a WTRU is configured for dual-carrieror multi-carrier operations, the following set of rules are proposed,which may be used in any order and in any combination.

First, when power scaling is applied to any carrier, then the WTRU doesnot create any new E-DCH transport blocks for any carrier other than theanchor carrier. This results in the E-DPDCH and E-DPCCH not beingtransmitted on these carriers. This may be achieved, for example, by notperforming E-TFC selection for any of the supplementary carriers whenpower scaling is being applied;

Second, when power scaling is being applied to any supplementarycarrier, then the WTRU does not create any new E-DCH transport block forany carrier other than the anchor carrier. This results in the E-DPDCHand E-DPCCH not being transmitted on these carriers. This may beachieved, for example, by not performing E-TFC selection for any of thesupplementary carriers when power scaling is being applied.

Third, when power scaling is applied to any carrier, the WTRU does notcreate any new E-DCH transport blocks. This may be achieved, forexample, by not performing E-TFC selection at all when power scaling isbeing applied. This results in the E-DPDCH and E-DPCCH not beingtransmitted on any carrier.

With respect to the above described rules, power scaling being appliedmay refer to power scaling being applied during a pre-defined orconfigured number of slots. Alternatively, power scaling being appliedmay also refer to the total power scaling applied being larger than apre-defined or configured value.

With respect to the above rules, when no E-DCH transport block has beentransmitted on a carrier due to power limitation, the carrier may bedeactivated (e.g., the WTRU may stop transmitting the associated DPCCH).

Described herein are power scaling mechanisms to reduce power imbalancebetween multiple carriers. For Dual Carrier-High-Speed Uplink PacketAccess (DC-HSUPA), due to independent inner and outer loop powercontrols, different load and traffic on carriers, two carriers may betransmitted with large power imbalance. When this occurs, thesignal-to-noise ratio (SNR) of the carrier with the smaller power may bedeteriorated by the presence of the other carrier due to common ErrorVector Magnitude (EVM) sources. In particular, any impairment leading tocarrier leakage may decrease the SNR at the transmitter output. Onepossible outcome of such output signal degradation consists of apotentially significant degradation of the DPCCH SNR on the victimcarrier, i.e., the lower power carrier. This signal degradation may beexacerbated when the output DPCCH power is low, such as when the WTRU isclose to the Node-B. At the system-level, this may likely result in theNode-B sending transmit power command (TPC) up commands to increase theoutput DPCCH power, leading to an increase in noise rise, a loss ofheadroom for the WTRU and thus a reduction of the uplink capacity.

This signal degradation may be modeled as follows. Define the power ofthe transmitted DPCCH on the victim carrier as P_(DPCCH), the adjacentcarrier interference ratio as G_(ACLR), the path gain to the Node-B asG_(Path), the interference power plus noise level at the Node-B P_(IN),the DPCCH signal-to-interference ratio (SIR) target at the Node-B asSIR_(D,T), and the total power transmitted on the aggressor carrier asP_(tot,a). The total adjacent carrier interference power may be given bythe following:P _(ACLR) =P _(tot,a) ×G _(ACLR).  Equation (1)

The DPCCH signal-to-interference ratio (SIR) as measured at the Node-B,SIR_(DPCCH), may be expressed as:SIR_(DPCCH)=(P _(DPCCH) ×G _(Path))/(P _(ACLR) ×G _(Path) +P_(IN)).  Equation (2)

This shows that when a victim carrier suffers from adjacent carrierinterference (due for example to a power imbalance) the SIR measured atthe Node-B is reduced due to the reduction of SIR at the transmitter.

The ratio of DPCCH power to reach the same SIR target at a Node-B in thepresence of inter-carrier interference and in the absence ofinter-carrier interference may be expressed as:ΔP _(DPCCH)=(P _(ACLR) ×G _(Path) +P _(IN))/P _(IN)=1+(P _(ACLR) ×G_(Path))/P _(IN).  Equation (3)

There are a number of different scenarios which may lead to powerimbalance. In a first scenario, E-TFC selection is performed for twocarriers. This scenario may occur when the WTRU has data to transmit andboth carriers may transmit E-DCH data in the next TTI.

In a second scenario, E-TFC selection is performed for only one carrier.This scenario may occur when the WTRU has data to transmit, but only oneof the two carriers is available for E-DCH transmission due to, forexample, that the next HARQ process for one of the carriers may not beenabled or activated (from the L2 or L3 perspective). It may also be dueto the fact that the next HARQ process for one of the carriers is inretransmission mode, the grant of the one carrier is zero or the mediumaccess control (MAC) DTX is being applied to one of the carriers but notto the other carrier.

In a third scenario, no E-TFC selection is performed. This scenario mayoccur in a given slot when no E-DCH transmission is taking place andwhen control channels (e.g., the DPCCH and HS-DPCCH) are beingtransmitted over both carriers simultaneously. That is, both carriersare transmitting at least the DPCCH.

To alleviate this undesirable loss of signal quality at the transmittercaused by any of these scenarios, power scaling may be used to keep thepower imbalance within a pre-defined range, reducing the undesirabledecrease in output SNR on the victim carriers.

In one example of using power scaling to reduce power imbalance, anumber of mechanisms are described where it may be assumed that a givenpower imbalance threshold value is configured at the WTRU. Thesemechanisms may be applicable in any order and in any combination.

The power imbalance threshold may be an indication of how much powerdifference may be tolerated between the two carriers. Alternatively,this power imbalance threshold may be an indication of how much powerdifference may be tolerated between one carrier and a given channel(e.g., DPCCH or PUCCH) on a victim carrier. This threshold value mayalso be calculated by the WTRU, and may depend on one or more parametersand in any combination. The parameters may include, but are not limitedto, for example, the WTRU DPCCH transmission power, the total WTRUtransmission power (as per its category or as configured by thenetwork), the total power transmitted (e.g., over the last TTI, averagedover the last three slots or averaged over a pre-defined time interval),the common pilot channel (CPICH) power as measured by the WTRU, the pathloss estimated by the WTRU from knowledge of the absolute CPICH power orother means, an offset or threshold value configured by the network andreceived by the WTRU via RRC signaling, and a pre-defined offset orthreshold value pre-defined in the standards specifications.

A value for this threshold may be prescribed by the specifications, andthe WTRU may be preconfigured with this value. Alternatively, thenetwork may signal this value via RRC signaling, for example as part ofa reconfiguration message for dual-carrier or multi-carrier uplinkoperations. The mechanisms described may also be applicable even if thesignification of this threshold value is different.

In this method, the WTRU may be configured to scale the power for eachcarrier to maintain the power imbalance equal to or below a threshold.This threshold may be calculated by the WTRU, configured by the network(in which case the WTRU has to first receive the configuration via RRCsignaling) or pre-defined in the specifications.

The WTRU may calculate the total power transmitted over each carrier.For example, the total transmitted power on the anchor carrier may becalculated as follows:P _(tot1) =P _(DPCCH,1) +P _(HS-DPCCH) +P _(E-DPCCH,1) +P _(E-DPDCH,1);and  Equation (4)P _(tot2) =P _(DPCCH,2) +P _(E-DPCCH,2) +P _(E-DPDCH,2)  Equation (5)where P_(DPCCH,k), P_(E-DPCCH,k) and P_(E-DPDCH,k) are the DPCCH,E-DPCCH and E-DPDCH powers transmitted over carrier index k=1,2,respectively. P_(HS-DPCCH) is the power of the HS-DPCCH (transmittedover carrier 1, although it may be transmitted over more than onecarrier).

If the difference between P_(tot1) and P_(tot2) is larger than a certainthreshold, that is if:|P _(tot1) −P _(tot2) |>P _(Th);  Equation (6)then power scaling is applied to reduce the total imbalance equal to orbelow the threshold value P_(Th). Alternatively, the power imbalance maybe expressed as |P_(tot1)−P_(tot2|≥P.)

Power scaling may be applied to the carrier with the largesttransmission power. For the purpose of this description, it may beassumed without loss of generality that the first carrier has thelargest power such that P_(tot1)−P_(tot2)>P_(Th) holds.

In this case, the WTRU applies power scaling to the E-DPDCH on carrier 1such that P_(E-DPDCH,1) is reduced. The power reduction is achieved byreducing the value of the E-DPDCH gain factor for the first carrieruntil the power difference is smaller (or smaller than or equal to) thethreshold, that is P_(tot1)−P_(tot2)<P_(Th) (orP_(tot1)−P_(tot2)≤P_(Th)), or until the minimum value of the gain factoris reached. Optionally, a special minimum value of the gain factor isconfigured for use with power imbalance power scaling only. Optionally,in case the gain factor of the E-DPDCH before scaling is already belowthe minimum value configured, no scaling may be applied to that carrier.

If, after this E-DPDCH power scaling, the power difference is stilllarger than (or larger than or equal to) the threshold, additional powerscaling may be applied. In a more explicit form, it is assumed thatP_(tot1) was reduced to P_(tot1)′ by the power scaling. Then in thissituation, P_(tot1)′−P_(tot2)<P_(Th) still holds and additional powerscaling is required.

The additional power scaling may consist of one or more approaches. Inone approach, the WTRU may apply equal power reduction to all thechannels carried over the first carrier. In another example approach,the WTRU may increase power on the second carrier using one or moremethods. In another example approach, the WTRU may increase the power ofthe DPCCH on the second carrier. In another example approach, the WTRUmay increase the power of the E-DPDCH on the secondary carrier (that is,beyond what is prescribed by the selected transport block size). Inanother example approach, the WTRU may apply equal power increase to allthe channels carried over the second carrier. In another exampleapproach, the WTRU may increase the power of the control channels onlyon the second carrier when the maximum transmit power is not exceeded.

In one example embodiment of additional power scaling, the WTRU maycalculate the power imbalance that needs to be compensated for byadditional power scaling. For example, the WTRU may calculate theadditional power that needs to be reduced, P_(add), by using thefollowing:P _(add) =P _(tot1) ′−P _(tot2) −P _(Th).  Equation (7)

The WTRU may then reduce the power of the first carrier by that amount(or slightly more depending on the quantization levels to ensure thatthe resulting power difference meets or is below the threshold) viapower scaling. This may be achieved, for example, by scaling allchannels of that carrier by the same scaling factor.

In another example embodiment, the WTRU may calculate the difference inpower between the total transmitted power on one carrier and the powerof the DPCCH on the other carrier. A power imbalance is detected whenfor at least one of the power difference is larger than a threshold. Inmore particular terms, the WTRU calculates the difference between thetotal power in carrier 1 and the DPCCH power in carrier 2 and betweenthe total power in carrier 2 and the DPCCH power in carrier 1:P ₁₂ =P _(tot1) −P _(DPCCH,2,);  Equation (8)P ₂₁ =P _(tot2) −P _(DPCCH,1,);  Equation (9)where P_(tot1), P_(tot2), P_(DPCCH1) and P_(DPCCH2) are defined above.The WTRU may then verify if a power imbalance condition occurs. This maybe achieved by comparing P₁₂ and P₂₁ to a threshold such that ifP₁₂>P_(Th) or P₂₁>P_(Th) then a power imbalance condition exists. Forexample, if P₁₂>P_(Th), then carrier 1 interferes with carrier 2 andcarrier 1 is the aggressor and carrier 2 the victim.

One consequence of such power imbalance is that one carrier interfereswith the other carrier at the transmitter. This results in a lower DPCCHSNR at the Node-B, which in turn may request the WTRU to raise its DPCCHpower on that victim carrier. This results in lower headroom for theWTRU and ultimately a loss of capacity on the uplink.

In one example method, to reduce the impact of such a power imbalance,the WTRU may reduce the power of the aggressor carrier such that thepower difference meets or is below the threshold. In this method, theWTRU may receive a configuration message (e.g., via RRC signaling)containing parameters related to the calculation of the amount of powerreduction. Such parameters may include, for example, one or more of athreshold value, a power offset, an interference power level, and a pathloss measurement. The WTRU may then calculate the power reduction basedon a combination of one or more elements. For example, the WTRU may usethe DPCCH power transmitted on the victim carrier. In another examplemethod, it may use an estimate of the path loss (e.g., obtained usingexisting measurements). In another example method, it may use one ormore parameters transmitted by the network (such as threshold value, apower offset, an interference power level, an interference plus noisepower level or a path loss measurement). In another example method, itmay use the total power transmitted on the aggressor carrier. In anotherexample method, it may use a carrier leakage parameter, which may beWTRU-specific, fixed by the specifications or configured by the networkvia RRC signaling.

In an example embodiment, if carrier 1 is the aggressor and P_(tot1) isthe total power transmitted over the carrier 1, and if the carrierleakage ratio is G_(ACLR), the path gain is G_(Path), the interferencepower plus noise level at the Node-B is P_(IN), and the threshold valueis Th, then using the second term in equation (3), the WTRU maycalculate a power reduction factor α for the aggressor carrier such thatthe following equation is respected:αP _(tot1)<(Th×P _(IN))/(G _(ACLR) ×G _(Path))  Equation (10)

This WTRU-calculated power reduction may be applied to the E-DPDCH onlyon the aggressor carrier. The WTRU may not apply this power reduction toreduce the power of the E-DPDCH further than the minimum value allowedby the conventional power scaling procedure. Alternatively, the WTRU mayapply this power reduction equally to all channels on the aggressorcarrier.

In another example method, the WTRU may apply a fixed power reduction tothe aggressor carrier E-DPDCH when a power imbalance condition isdetected. The WTRU may receive the value of the fixed power reductionfactor via RRC signaling. Alternatively, the WTRU may use a powerreduction factor specified by the standards.

In another example method, the WTRU may raise the power of the DPCCH onthe victim carrier when it detects the power imbalance condition. Thismay potentially avoid delays in raising the DPCCH power to the targetlevel due to the power control latency and limited DPCCH power increasestep size. This may be achieved, for example, by the following method.The WTRU may calculate the power offset to be added to the DPCCH on thevictim carrier in a similar way as described above for calculating thepower reduction factor. For example, the DPCCH power factor applied tothe victim carrier, φ, may be calculated via the following formulation:φ=1+(P _(tot1) ×G _(ACLR) ×G _(Path))/P _(IN)  Equation (11)

In another example approach, a fixed power factor may be applied toDPCCH of the victim carrier when a power imbalance condition isdetected. The WTRU may receive this power factor via RRC signaling.Alternatively, the WTRU may use a power factor specified by thestandards.

In another example approach, the WTRU may be power-limited when a powerimbalance condition occurs. In such cases, the WTRU may reduce the powerof the E-DPDCH on the aggressor carrier thereby liberating part of thepower for the victim carrier, which it may use to properly send its datainformation. Thus, the power adjustment for power imbalance may beperformed in this case before the conventional power scaling procedure.Optionally, on the network side, a Radio Network Controller (RNC) mayconfigure the Node-B with a different DPCCH SIR target when the WTRU isoperating with dual-carrier. The Node-B may use this value when thesupplementary carrier is activated and revert to the single-carrierDPCCH SIR target when the supplementary carrier is de-activated. Thisdifferent DPCCH SIR target may be signaled by the RNC by means of a SIRoffset which is applied to the DPCCH SIR target at the Node-B for agiven WTRU when its supplementary carrier is activated.

Described herein are methods when the WTRU detects a power imbalance andnotifies the network. In one example embodiment, the WTRU may detect apower imbalance condition and signal it to the network. To declare thata power imbalance condition exists, the WTRU may compare the powerdifference between the total power transmitted on the first carrier andthe total power transmitted on the second carrier to a threshold value.Alternatively, the WTRU may compare a power difference (between thetotal power transmitted on one carrier and the DPCCH power transmittedon the other carrier) to a threshold value and vice versa. The WTRU mayperform these operations every radio slot or every TTI. If any of thepower differences are above the threshold, the WTRU notifies thiscondition to the network. Optionally, the WTRU may count the number ofsuccessive radio slots (or TTI) for which the power imbalance conditionis detected. The count may be reset every slot (or TTI) where the powerimbalance condition is not detected. When the count reaches a certainvalue, the WTRU may notify the power imbalance condition to the network.Alternatively, the WTRU may count the number of radio slots (or TTI) forwhich the power imbalance condition is detected during a configuredperiod of time (sliding window). When the count is above a configuredthreshold, the WTRU notifies the network that a power imbalancecondition has been detected. For example, when the WTRU counts N or morepower imbalance events in the last M TTIs, then the WTRU notifies thenetwork.

The notification may be sent via a new field in the MAC-i or MAC-eheader as it terminates at the Node-B. Alternatively, the WTRU may sendan RRC message to the network indicating the conditions. This RRCmessage may be a measurement report. In another alternative, the WTRUmay send the information via system information (SI) in which casedetection of the power imbalance situation acts as a trigger for sendingan SI. The information may be carried, for instance, in one of theunused bits in the SI for the secondary carrier. Alternatively, a newfield is introduced in the SI or some combinations of bits arere-interpreted.

In another example embodiment, assuming the existing Adjacent ChannelLeakage Ratio (ACLR) requirements for single carrier are maintained fordual carrier HSUPA, a total transmission power based method may be usedto handle the maximum power different between carriers. In thisembodiment, when the total transmission power does not exceed the WTRUmaximum power, then the inner and outer loop power control mechanismhandles the power imbalance. And when the total transmission powerexceeds the WTRU maximum power, the power reduction and power scalingand corresponding E-TFC methods as described herein are selected tohandle it.

For DC-HSUPA, the WTRU may share its total power over two carriersduring dual carrier operation. There are potential sources ofnonlinearity in the front end, which may include power amplifier, mixer,and other components, depending on the implementation. Generallyspeaking, compared to single carrier HSUPA, the SNR of DC-HSUPA degradesnot only because dual carriers share the total power, but also becausedual carriers modulate each other and contribute to ACLR. The ACLR maybe increased as a particular hardware configuration is alternatelydriven by a multi or dual carrier signal and by a single carrier signalwith the same total power. Therefore, when the maximum power differencein dual carriers occurs, there is a potentially significant degradationof the DPCCH SNR on the victim carrier due to the big spectral leakagefrom the aggressor carrier. In order to avoid this, the acceptable ACLRlike the existing ACLR requirements for single carrier need to bemaintained for DC-HSUPA.

As part of this embodiment, the Node-B (UTRAN) may be configured toresolve the power imbalance issue by ensuring that the difference in ULDPCCH received power on the two carriers lies within a given thresholdfor a given WTRU by using the existing power control mechanism (i.e.,via DL TPC commands sent over Fractional Dedicated Physical Channel(F-DCPH)). This threshold may be preconfigured or signaled to Node-B bythe RNC.

An example realization to maintain the UL DPCCH received powerdifference between the two carriers below a given threshold is describedherein. When the difference in UL DPCCH received power of thedual-carrier is bigger than the given threshold, the Node-B compares theestimated DPCCH SIR of victim carrier to its DPCCH SIR target plus theoffset and generates TPC commands. This may result in the possibility ofincreasing the DPCCH power of the victim carrier and decrease the powerimbalance between the dual-carrier. When the difference in UL DPCCHreceived power of the dual-carrier is no more than the given threshold,the conventional power control may be run independently on each carrier,i.e., without offsetting the DPCCH SIR target. For example, let: 1)SIRTarget1 and SIRTarget2 represent the SIR targets configured for eachcarrier (note that a single SIRTarget may be configured, in which caseSIRTarget1=SIRTarget 2); 2) Rx1 and Rx2 represent the measured UL DPCCHreceived power for carrier 1 and carrier 2, respectively; 3)MAX_DPCCH_DELTA represent the maximum desired difference between Rx1 andRx2; and 4) TARGET_OFFSET represent the offset used to adjust theSIRTarget1 or SIRTarget2 given by the higher layer.

Then, the proposed two independent inner loop power control method fordual carriers may take the following form shown in Table 1.

TABLE 1 a.  If (Rx1 − Rx2 > MAX_DPCCH_DELTA) i. SIRTarget1_current =SIRTarget1 ii. SIRTarget2_current = SIRTarget2+ TARGET_OFFSET iii. If(SIR1 < SIRTarget1_current) 1. Then TPC1 is set to UP iv. Else TPC1 isset to down v. If (SIR2 < SIRTarget2_current) 1. Then TPC2 is set to UPvi. Else TPC2 is set to down b.  Else if (Rx2 − Rx1 > MAX_DPCCH_DELTA)i. SIRTarget1_current = SIRTarget1 + TARGET_OFFSET ii.SIRTarget2_current = SIRTarget2 iii. If (SIR1 < SIRTarget1_current) iv.Then TPC1 is set to UP v. Else TPC1 is set to down vi. If (SIR2 <SIRTarget2_current) vii. Then TPC2 is set to UP viii. Else TPC2 is setto down c.  Else i. SIRTarget1_current = SIRTarget1 ii.SIRTarget2_current = SIRTarget2 iii. If (SIR1 < SIRTarget1_current) 1.Then TPC1 is set to UP iv. Else TPC1 is set to down v. If (SIR2 <SIRTarget2_current) 1. Then TPC2 is set to UP vi. Else TPC2 is set todown.

The inner loop power control method shown in Table 1 for dual carriersmay ensure the difference in UL DPCCH received power on the two carrierslies within a given threshold while meeting the SIRtarget qualities onboth carriers. The method may be modified to achieve the same goal byreducing the SIRtarget of the aggressor carrier, which may not befavorable from a quality of service (QoS) perspective.

In another example realization of a joint UL dual carrier inner looppower control method, let: 1) SIR1 and SIR2 denote the measured SIRlevels on carriers 1 and 2 respectively; 2) SIRTarget1 and SIRTarget2represent the SIR targets configured for each carrier (note that asingle SIRTarget may be configured, in which case SIRTarget1=SIRTarget2); 3) Rx1 and Rx2 represent the measured UL DPCCH received power forcarrier 1 and carrier 2, respectively; 4) StepSize represent theincrease/decrease in power that is apply by the WTRU following an UP orDOWN command by the Node-B; 5) TPC1 and TPC2 represent the UP/DOWN TPCcommands that the Node-B generated for carrier 1 and carrier 2. TPC1 andTPC2 are the output of the joint inner loop power control method; and 6)MAX_DPCCH_DELTA represent the maximum desired difference between Rx1 andRx2.

Then, the jointly determined inner loop power control commands may bederived as shown in Table 2.

TABLE 2 a.  If (SIR1 < SIRTarget 1) and (SIR2 < SIRTarget2) i. Then TPC1is set to UP and TPC2 is set to UP b.  Else If (SIR1 < SIRTarget 1) and(SIR2 > SIRTarget2) i. If (Rx1 < Rx2), 1. Then TPC1 is set to UP andTPC2 is set to DOWN ii. Else (i.e. Rx1 > Rx2) 1. If (Rx1 − Rx2 +2*StepSize) < MAX_DPCCH_DELTA a. Then TPC1 is set to UP and TPC2 is setto DOWN 2. Else a. TPC1 is set to UP and TPC2 is set to UP c.  Else If(SIR1 > SIRTarget 1) and (SIR2 < SIRTarget2) i. If (Rx1 > Rx2), 1. ThenTPC1 is set to DOWN and TPC2 is set to UP ii. Else (i.e. Rx1 < Rx2) 1.If (Rx2 − Rx1 + 2*StepSize) < MAX_DPCCH_DELTA a. Then TPC1 is set toDOWN and TPC2 is set to UP 2. Else a. TPC1 is set to UP and TPC2 is setto UP d.  Else If (SIR1 > SIRTarget 1) and (SIR2 > SIRTarget2) i. ThenTPC1 is set to DOWN and TPC2 is set to DOWN.

This example method prioritizes reaching the SIRtarget quality on eachcarrier over meeting the maximum difference in power per carrier. Themethod may be modified to reach the maximum carrier power differencemore quickly at the expense of not meeting the SIRtarget on one or bothcarriers.

Optionally, the Node-B may want to ensure the difference in the totalreceived power (including E-DPDCH, E-DPCCH and/or HS-SCCH) on eachcarrier for a given WTRU is within a predetermined threshold. In oneexample embodiment, the Node-B may apply the UL DPCCH receive powermatching method and ensure that the difference in scheduling grantsprovided for each carrier lies within a certain threshold. In analternative embodiment, the Node-B may determine the inner loop powercontrol commands for UL DPCCH independently for each carrier (e.g., bysimply comparing the received SIR to the target SIR on each carrier),and determine scheduling grants jointly across the two carriers byensuring that the difference in total receive power from the WTRU onboth carriers, assuming scheduling grants are fully utilized, lieswithin a predetermined threshold.

In all cases, the maximum power difference thresholds may bepre-configured (i.e., pre-defined “hard” values) or configured by theRNC through signaling over the Iub interface.

Described herein is multi-mode power scaling. During radio-linkestablishment of a secondary UL carrier, the WTRU may transmit the DPCCHwith power determined by the TPC commands received on the associateddownlink F-DPCH. Concerns related to potential unlimited DPCCH ramp-updue to radio-link synchronization failures at the Node-B have beenraised, where a power-limit imposed on the DPCCH power of the secondarycarrier was suggested as a means to resolve the issue.

Accordingly, a multi-mode power scaling approach is described herein.Although this multi-mode power scaling approach is proposed in thecontext of DC-HSUPA, it is applicable to other technologies.

The example multi-mode power scaling method consists of two or morepower scaling modes: 1) one or more triggers to alternate power scalingmode; and 2) a set of rules dictating how the power scaling mode changeswith respect to possible triggers.

The power scaling mode may consist, for instance, of any of the powerscaling methods described herein or in other documents such as the 3GPPspecifications. The WTRU may obtain the set of triggers and rules fromthe specifications or receive the set of triggers and rules via aconfiguration message by the network (e.g., via RRC signaling).

When the WTRU operates in one of the power scaling modes, it may receivea trigger to change the power scaling mode. The WTRU may change thepower scaling mode at the time determined by the rules and startapplying power scaling according to the new mode.

In a first example, the first power scaling mode consists of scalingpower of the secondary carrier first. The second power scaling modeconsists of scaling the power of the carrier with the largest DPCCHpower first. The trigger and rules may be defined as: 1) upon secondarycarrier activation, the WTRU may use the first power scaling mode; and2) after a timer has expired, the WTRU may use the second power scalingmode.

The timer may be pre-configured in the specifications or the WTRU mayreceive its value via RRC signaling. The WTRU may start the timer whenthe WTRU starts UL transmission, or some time afterwards, for example,when the higher layers consider the downlink physical channelestablished.

Although features and elements are described above in particularcombinations, each feature or element can be used alone without theother features and elements or in various combinations with or withoutother features and elements. The methods or flow charts provided hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable storage medium for execution by ageneral purpose computer or a processor. Examples of computer-readablestorage mediums include a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs).

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, radio networkcontroller (RNC), or any host computer. The WTRU may be used inconjunction with modules, implemented in hardware and/or software, suchas a camera, a video camera module, a videophone, a speakerphone, avibration device, a speaker, a microphone, a television transceiver, ahands free headset, a keyboard, a Bluetooth® module, a frequencymodulated (FM) radio unit, a liquid crystal display (LCD) display unit,an organic light-emitting diode (OLED) display unit, a digital musicplayer, a media player, a video game player module, an Internet browser,and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB)module.

What is claimed is:
 1. A wireless transmit/receive unit (WTRU)comprising: a processor configured to determine transmission powerlevels for a plurality of uplink channels of a plurality of uplinkcomponent carriers, wherein the plurality of uplink channels include aphysical uplink shared channel (PUSCH) and a physical uplink controlchannel (PUCCH), wherein the plurality of uplink component carriersinclude a primary component carrier and a secondary component carrier;wherein, on a condition that a maximum transmission power level isexceeded, one or more transmission power levels of the plurality ofuplink channels are scaled; wherein a transmission power level of aPUSCH transmission without control data is scaled before a PUSCHtransmission with control data and the PUSCH transmission withoutcontrol data is scaled before a PUCCH transmission with control data;wherein the secondary component carrier is scaled before the primarycomponent carrier; and a transmitter configured to transmit on theplurality of uplink channels at the determined transmission powerlevels.
 2. The WTRU of claim 1, wherein the PUCCH is transmitted on theprimary component carrier.
 3. The WTRU of claim 2, wherein atransmission power level of the PUCCH is not scaled on the conditionthat an uplink maximum transmission power level is exceeded by a totalWTRU transmit power.
 4. A method performed by a wirelesstransmit/receive unit (WTRU), the method comprising: determining, by theWTRU, transmission power levels for a plurality of uplink channels of aplurality of uplink component carriers, wherein the plurality of uplinkchannels include a physical uplink shared channel (PUSCH) and a physicaluplink control channel (PUCCH), wherein the plurality of uplinkcomponent carriers include a primary component carrier and a secondarycomponent carrier; wherein, on a condition that a maximum transmissionpower level is exceeded, one or more transmission power levels of theplurality of uplink channels are scaled; wherein a transmission powerlevel of a PUSCH transmission without control data is scaled before aPUSCH transmission with control data and the PUSCH transmission withoutcontrol data is scaled before a PUCCH transmission with control data;wherein the secondary component carrier is scaled before the primarycomponent carrier; and transmitting, by the WTRU, on the plurality ofuplink channels at the determined transmission power levels.
 5. Themethod of claim 4, wherein the PUCCH is transmitted on the primarycomponent carrier.
 6. The method of claim 5, wherein a transmissionpower level of the PUCCH is not scaled on the condition that an uplinkmaximum transmission power level is exceeded by a total WTRU transmitpower.